four type of cast

four type of cast

syntax:

reinterpret_cast <new_type> (expression)

dynamic_cast <new_type> (expression)

static_cast <new_type> (expression)

const_cast <new_type> (expression)

1.reinterpret_cast

to interpret a value as a different type.

• pointer->intergers
• intergers-> pointer
• pointers from one type to another type

2.dynamic_cast

used with pointers and references to objects

we can not cast a base class to derived class

CBase b;

CBase* pb;

CDerived d;

CDeried* pd;

pb = dynamic_cast<CBase*>(&d);

pd = dynamic-cast<CDerived>(&b);  //wrong: b is base class and it does not have the derived class parts

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CBase* pba = new CDerived;

CBase* pbb = new CBase;

CDerived* pd;

pd = dynamic_cast<CDerived*>(pba);

pd = dynamic_casr<CDerived*>(pbb);  //wrong; pbb is base class and can not cast to a derived class

3.static_cast

perform automatically and can perform conversions between pointers to related classes, not only from the derived class to its base, but also from a base class to it derived.

it will have some run-time errors;

4.const_cast

这种类型转换对常量const 进行设置或取消操作：

this type of casting manipulates the constness of an objects,either to be set or to be removed.

for example, in order to pass a const argument to a function that expects a non_constant parameter:

const char* c ="sample text"; // const

print(const_cast<char*> (c));  cast the const char* to a char*